Fluid pressure switch



Dec. 21, 1948.

Filed Jan, 4, 1946 5 8 45 g :22 86': I T 3;

6? If Ea Wflliam MRobz'sop 3 Patented Dec. 21, 1948 UNITED STATES PATENT OFFICE.

I I I r'nnrnra a szrlmswrrcn Q William M. ltobison, Mount Holly, 'N. I.

This invention has for its primary object the provision oi a simple and emciently operating mechanism for indicating when the oil supply of an internal combustion engine has become substantially exhausted, and for preventing, starting -of the engine until the oil supply has been replenished.

In accordancewith my invention, an automatically operative device is provided to operate directly in response to a change in pressure in the lubricating oil system of an internal combustion engine to cut out the ignition system for, and consequently stop, the engine in the event of an undue or abnormal decrease in the pressure of the lubricating system and thereby gives positive indication of the mentioned condition of the oil supply; and also to operate directly in response to vacuum created in the intake manifold of the engine to prevent cutting in of the ignition system and consequently starting of the engine until steps have been taken to eliminate the cause of the mentioned abnormal condition in the lubricating oil supply system.

My improved mechanism, as hereinafter more specifically described, includes a switch adapted to be electrically connected with the ignition system for an internal combustion engine, and] a positively-acting actuator for the switch adapted to operate automatically and directly on the switch in response to predetermined conditions extrinsic of the ignition system in which the switch is installed: the switch being held open by the actuator to permit the fiow of current through the ignition system in which it is installed but being closed to cut out the ignition system, all in response to predetermined pressure and suction conditions and in a manner which will be made manifest as the description proceeds.

The invention, both as to its organization and its method of operation, together with its above stated, and other, objects and advantages, will best be understood from the following detailed description read in connection with the accompanying drawing in which is illustrated what is presently considered the preferred embodiment of the invention, and wherein:

Figure 1 is a view in elevation of my improved oil supply indicating mechanism Figure 2 is an enlarged detail view partly in section and partly in elevation, and taken vertically through the device on substantially line 2-2 of Figure l; and

Figure 3 is a diagrammatic view illustrating an application of the invention.

On the accompanying drawing I have used the 4 cm. (01. zoo-us) reference character I to indicate the casing of my device. This casing is composed of a plurality of sections of circular, rimmed sections 0, I, l and O that are disposed in axial alignment and secured in assembly by two groups of screw bolts I0 and il. Bolts ill extend through the rim of easing section 6 and bolts ll extend through the rims of sections 9 and 8; the ends of all of the bolts thread into the rim of section I in the manner shown thereby securing all the parts together. So assembled, the rimmed sections form for the casing 5 chambers or compartments I2, I! and I4. Thus the construction and assembly of the casing is such that it is comparatively simple and inexpensive and admirably lends itself to the purpose for which designed.

Casing 5 is adapted to be installed between the pressure lubricating system and the intake manifold of an internal combustion engine. To that end a fitting I5 is tapped into casing I in the region of chamber 13 for connection to the line I. of' the pressure lubrication system, and a fitting I1 is tapped into the casing in the region of chamber for connection to the line It leading from the intake manifold, of the internal combustion engine.

Arranged within chamber I2 of casing I is a switch indicated generally by the reference numeral It. This switch embodies a fixed contact 20 suitably mounted in the mentioned chamber, and a movable contact 2| mounted on a pivoted arm 22 that is biased in the direction of the fixed contact by a spring 23. l-

An inverted substantially U-shaped bridge member 24 of dielectric material is secured by screws 25 within chamber l2 and straddles switch 22 in a manner to act as a stop therefor. 'Also anchored to the crown of bridge member 24 is one end of the aforementioned spring 23, the other end of which is looped about the pivot 2| for arm 22 in a manner to exert pressure on the arm for influencing it to swing toward the fixed contact 20. The pivot assembly for the switch arm is not oi the essence of this invention and hence is neither illustrated nor described herein in detail.

Switch It, as just described, is adapted to be placed in electrical connection with the ignition system of an internal combustion engine. Io that end contact 2| of the switch is electrically connected to the coil 21 of the ignition system through the medium of the aforementioned spring 2!, and a wire" that connects the anchored end of the spring to a binding post 2! that in turn is connected by a wire II to the coil some itaswillbeciearuponrcicrencetoriguresa and 8 of the drawing. As is apparent from the foregoing, when switch II is closed the ignition system will be cut out or rendered inoperative thus preventing starting of the engine until the switch is opened.

switch II is normally held open so as not to interfere with the normal operation of the mine through the medium of aligned. normally abutting push rods ii, 32 that are yieldably influenced by a spring 33 to act on the switch arm 22 in opposition to the action of spring 23 thereon.

However, it may be here mentioned, as hereinafter shown, that when the engine is running and the pressure in the lubricating oil system is normal, switch it is retained in open position in response to pressure in the lubrication system and rod 32 is retained in such spaced relation to rod II in response to the vacuum in the intake manifold of the engine as not to interfere with a complete closing of the switch in the event the lubricating oil supply or the pressure in the lubrication system for any reason falls below a predetermined amount or below normal. Also, and as will be hereinafter shown, by the arrangement contemplated by this invention immediate reopening of the switch it upon the stopping of the engine and consequent breaking of the vacuum in the fuel supply line is definitely precluded; and as will be apparent to those skilled in this art, such delayed re-opening of the switch is a highly desirable safety factor.

Continuing now with the details of construction, diaphragm 34 is secured between casing sections it and l and a diaphragm 35 is secured between casing sections 8 and I by the aforementioned bolts ll. Diaphragm 34 extends across chamber l3 above fitting i and at its center is secured and sealed with respect to the push rod Si by washers 38 arranged above and below the diaphragm. Diaphragm 35 extends across chamber it above fitting I1 and is secured and sealed at its center with respect to push rod 82 by washers ll, 38 disposed above and below the diaphragm as illustrated.

Within the chamber II is a power element in the formof an expansion spring 39 that is disposed concentrically of rod ii and at one end seats in a circular seat 40 formed concentric to the opening provided in the casing section i and through which rod 3i has a sliding fit. At its other end the spring 39 impinges on the washer ll above the diaphragm 34. Downward movement of rod II is limited, in an obvious manner, by a shoulder ll provided on the rod as shown.

The aforementioned spring ll is accommodated within a housing 42 formed on easing section I and at one end seats against the rimmed washer ll. Interposed between the lower end of spring 33 and the inward end of fitting i1 is one or more apertured discs 43. The purpose of discs 48 are to tension spring 33, the tension of the spring being adjusted or varied in proportion to the thickness and number of discs so used, as is believed to be apparent.

Chamber it receives oil from the lubrication system in which the casing i is installed through the fitting l5 below diaphragm 34. Chamber ll will also receive oil therein and above diaphragm II from chamber I 3 through a passage 44 provided in the body of easing section 8, and in which body is also formed an oil return duct or passage 45. A spring loaded valve ll, opening inwardly of chamber ll controls the flow through passage 44 and a similar valve ll, opening inwardly of chamber ll, passage II.

In the operation of my oil supply indicator. spring 33 acting through the rods 82, ll normally holds switch arm 22 slightly raised and contact 20, 2| separated; rod Ii at its upper end being held in pressure-exerting contact with an abutment lug ll of insulation material carried by the switch arm at the underside of the latter as indicated by broken lines in Fig re 2.

When pressure builds up in the lubrication system, as when the internal combustion engine is started, the lubricating oil pressure in chamber l3 increases, causing diaphragm 34 to increasingly flex upwardly and consequently further raise switch arm 22. Also the vacuum in the intake manifold of the engine will influence the diaphragm 35 causing the latter to flex downwardly. Thus with the engine running normally, the rods 3|, 32 are held sufiiciently spaced as to each other as to permit substantially free vertical movement of rod ii and downward movement thereof to the extent necessary to permit complete closing of switch [9 in the event the oil supply or pressure in the lubrication system falls below a predetermined amount or below normal.

Assuming now that the oil supply or pressure in the lubricating system for the engine begins to decrease, under such conditions there will be a comparable reduction of pressure on the underside of diaphragm 34. As this pressure decreases the thrust of spring 39 acting on diaphragm Il forces rod 3| downwardly and spring 11 at the same time forces switch arm 22 downwardly. Thus it will be apparent that as the oil supply and consequently the pressure in the lubrication system decreases switch contact 2| is gradually moved into circuit closing engagement with the fixed contact 20, and that the switch I! will attain fully closed position for cutting out the ignition circuit for the engine when the oil supply in the lubricating system has fallen to a predetermined minimum or below normal.

With the ignition circuit cut out in the manner just described, the engine will, of course, come to a stop, thereby warning the operator of the vehicle or the attendant, as the case may be, that the oil supply needs to be replenished. With the stopping of the engine, the vacuum in the fuel supply line therefor will be broken. When that condition obtains the thrust of spring 33 acting on diaphragm 35 will cause rod 32 to move upward and exert an upward thrust on rod 4! in a manner to cause the latter to urge contact 2| away from contact 20 in opposition to spring a.

The opening of switch I 9 in the manner described in the preceding paragraph, will be gradual by reason of the fact that the thrust of spring 33 on diaphragm 35 will be resisted by the oil in chamber i4 above the mentioned diaphragm. In this connection, it will be noted that as diaphragm 35 flexes in response to the action of spring 33, oil in the chamber ll will be forced therefrom into chamber II through duct II and upwardly opening check valve 47. Thus chamber ll above diaphragm II together with chamber l3 below diaphragm 34, and the valve-eontrolled ducts 44', 45, co-act to serve as a dashpot to delay the opening of the switch II and consequent restarting of the engine for a period suiiicient, to assure that the stopping of the engine will serve as a warning as intended. Further, as should be apparent from the foregoing. with my device there can be no continuous run- 4 controls the flow throulh specifically noted that switch it acts automatically to cut out and to cut in the ignition circuit in response to conditions of pressure in the oil lubrication system and to conditions of vacuum in the intake manifold, conditions which are extrinsic of the ignition system, of the internal combustion engine.

While I have herein shown a preferred embodiment of the invention, 1 am of course aware that various changes vmay be made within the scope of the claims hereto appended.

What I claim is:

1. An oil supply indicator for internal combustion engines comprising, a casing composed of a plurality of rimmed sections defining therebetween a plurality of chambers, a diaphragm spanning each of two adjacent chambers, a switch within a third chamber adapted to be electrically connected with an ignition circuit to provide an electrical connection between such circuit and the casing, said switch embodying a spring normallyholding it closed, a push rod for the switch connected to one of said diaphragms, a second switch push rod in alignment with the first push rod and connected to the other of said diaphragms, a spring acting directly on the first diaphragm to time it in a direction away'from the switch, a spring acting directly on the second diaphragm to urge it in the direction of the switch, the first mentioned diaphragm and push rod being arranged to exert pressure directly on the switch against the force of its spring in response to pressure conditions in the oil lubricating system, and the second mentioned push rod and diaphragm being in alinement with the first push rod and diaphragm to exert pressure on the switch through the first mentioned push rod in response to conditions of vacuum in the intake manifold, of an internal combustion engine; said casing being adapted to be connected in direct communication with the oil lubricating system and intake manifold of an internal combustion ensine.

2. For use with an internal combustion engine having an ignition system, a pressure lubrication system, and an intake manifold, an oil supply indicator comprising a casing adapted to be provide an electrical connection between such system and the casing, and an actuator for said switch comprising aligned push rods, one of said push rods being secured to one of said diaphragms, and the other of said push rods being secured to the other of said diaphragms.

3. An oil supply indicator for internal combustion engines comprising a casing divided into a plurality of chambers and adapted to be connected in direct communication with the oil lubricating system and intake manifold of an internal combustion engine, a normally closed switch located in one of the chambers and adapted to be electrically connected with the ignition,

system of an internal combustion engine, a diaphragm spanning each of two adjacent chambers, a push rod connected to one of said diaphragms and directly engageable with the switch to exert pressure, thereon in response to pressure conditions in the oil lubricating system for effecting an opening of the switch, and a second push rod secured to the second diaphragm and in axial contact with the first push rod to exert pressure on the switch through the firstmentioned push rod in response to conditions of vacuum in the intake manifold of the internal combustion engine.

4. For use with an internal combustion engine having an ignition system, a pressure lubrication system, and an intake manifold, a casing adapted to be connected with the pressure lubrication system and the intake manifold and embodying a plurality of chambers, a switchin one of the chambers embodying a stationary contact supported by the casing and a movable contact adapted to be electrically connected with the ignition system and movable into and out of electrical engagement with the stationary contact to thereby cut out and cut in said ignition system, and an actuator for the movable contact responsive to the pressure of lubricating oil in the casing and to the presence and absence of vacuum in the intake manifold to influence opening and closing of said switch, said actuator embodying diaphragms spanning each of two ediacent chambers and push rods respectively secured to the respective diaphragms, one of the push rods being arranged to exert pressure directly on the movable contact of said switch and the other of the push rods being arranged in alignment with the first push rod to exert pressure on the movable contact of the switch through the first-mentioned push rod.

WILLIAM H. ROBIBON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,444,403 Varley Feb. 6, 1928 1,456,863 Willis May 39, me 

